The present invention relates to a portable electric router, and more particularly, to the portable electric router capable of performing chamfering and groove forming operations with the employment of a rotary cutting bit.
FIGS. 1 and 2 show an example of a conventional portable electric router. As is well known in the art, a housing 12 is movably supported on a base 11 which guides the router when sliding over a workpiece such as wood material 20. A motor housed in the housing 12 has a motor shaft 2, whose lower end is provided with a chuck 5 for mounting a cutting bit 6 which may take on various forms. The bit 6 is rotated by rotation of the motor and can therefore be used for beveling or chamfering work and groove forming work.
As best shown in FIG. 2, the motor includes a stator 7 having a stator coil and a stator core, and an armature 1 having an armature coil and an armature core. A cooling fan 3 is mounted to the lower portion of the armature shaft, i.e., the motor shaft 2. The cutting bit 6 is mounted onto the lower end of the armature shaft 2 by the chuck 5.
A portable electric router constructed as described above is a tool for performing chamfering or grooving work on a workpiece made of, for example, wood. This is an especially indispensable tool for producing furniture. This type of tool must be highly efficient at cutting, must be lightweight, and easy to maneuver, and capable of producing good finished surfaces. Of these basic capabilities, if the finishing level is sufficient to make a product, normally cutting efficiency is most demanded for improving production.
Generally, increasing the lamination thickness of the motor is used as a means to enhance the cutting efficiency, which leads to enlargement of the motor size and increase in its rotation power. However, enlarging the size of the motor increases the overall weight of the router. The core and coil of the stator and the armature increases and so does the cost of production. Resultant electric router does not provide sufficient transportability and operability or workability, those being other requisite factors.
In another aspect, the cutting bit normally has two cutting edge portions. In operating the router which assembles such cutting bit, load variation will occur. The fluctuation of load may degrade operability of the router and quality in the finished product.